Any gains in active and passive range of motion during the first year of life may improve these long-term shoulder outcomes. The investigators have instituted a program of early passive repositioning mostly using a custom Sup-ER (Supination and External Rotation) splint during early growth and development to improve arm position and range of motion where ER and Sup are weak. In compliant patients in a pilot study, the speed and strength of recovery of ER and Supination are improved compared to historical controls. It is a novel splint and protocol designed by the investigators. This study is a randomized controlled trial to evaluate the use of the Sup-ER protocol in multiple centres over a two year period by assessing the arm function at common time points in recovery. The subjects are randomized to the Sup-ER protocol or the currently accepted standard treatment.